This questionable self-defense product is called "The Stunning Ring". It contains a stinging powder that can be ejected using a latch on the side:

The spray causes inflammation of the eye capillaries and all other mucous membranes, resulting in immediate temporary visual impairment, difficult breathing, coughing, choking, sneezing, severe burning sensations to the eyes, nose, throat and skin, and nausea, with acute symptoms and discomfort lasting for 45 minutes. There is no permanent damage.

Well it's illegal in more countries than it's legal. It kills a small percentage of people that is is used on (Very, very small, 1 or 2 a year in USA but still some fatalities).

The link is for a classy website called Self Defense Products.As well as the Tasers (sadly out of stock), police expandable batons, lock-picks and handcuffs they also sell such essential self defense products as swords, crossbows, throwing axes and Sony alarm clock radios containing hidden video cameras and recorders - the perfect Christmas present for enjoying your friends sex lives.Now thats what I call Neato.